The present invention relates to an enzyme immunoassay method using an adenosine triphosphate (hereinafter referred to as "ATP")-generating enzyme as a labeling enzyme.
Analytical methods using chemiluminescence or bioluminescence are employed as methods for microanalysis of living body components. In particular, the quantum yield of luminous reactions utilizing the enzyme system of an organism is very high, and the luminous reactions are variously used in very highly sensitive analytical methods.
On the other hand, as to the application of luminous reactions to enzyme immunoassay (hereinafter referred to as "EIA"), chemiluminescence is mainly applied but several attempts have been made to apply bioluminescence to EIA. For example, there has been developed a method which comprises labeling an enzyme capable of generating a coenzyme which takes part in a luminous reaction, such as reduced form nicotinamide adenine dinucleotide, connecting the same to a bio-luminescence system, and thereby introducing bio-luminescence into EIA. This method is useful as a very highly sensitive EIA method because of the amplifying effect of the labeling enzyme. For example, it has been reported that an EIA method using glucose dehydrogenase as a labeling substance permits detection of 2.5.times.10.sup.-12 g of 17-.alpha.-hydroxyprogesterone (Bunseki Kagaku, vol. 34 (1985), 6-10).